Conversion of hydrocarbon oils



y 1939. K. SWARTWOOD CONVERSION OF HYDROCARBON OILS Filed Feb. 15, 1957CONDENSER FRACTIONATOR VAPORIZING AND SEPARATING CHAMBER FURNACE 39,

82 RECEIVER INVENTOR KENNETH SWART WOOD CONDENSEF FURNACE 7,

ATTORNEY Patented May 16, 1939 UNITED STATES PATENT OFFIQE CONVERSION OFHYDROCARBON OILS Kenneth Swartwood, Chicago, Ill., assignor to UniversalOil Products Company, Chicago, 111., a corporation of DelawareApplication February 15, 1937, Serial No. 125,799

7 Claims.

or the separation of products resulting from the ditions.

relatively mild cracking of such oil, accompanied by the selectivecracking of said relatively lowboiling and high-boiling componentsunderindependently controlled cracking conditions, reduction of residualliquid conversion products of the process to coke and further crackingof the intermediate liquid conversion products of the process togetherwith said relatively high-boiling components of the charging stock.

One of the features of the invention is the flexibility cf the processwhich it provides with respect to the variety and range of materialswhich may be produced. The operating conditions may be varied to suitthe type of oil undergoing treatment and to suit varying economic con-For example, the process may be oper ated to produce one, two or threegrades of gasoline and the residual product of the process may compriseeither coke or liquid residue, or both, and various grades of liquidresidue, such as asphaltic material, lubricating stock, and variousgrades of fuel oilmay be produced.

In the initial step of the process to which charging stock of relativelywide boiling range, such as crude petroleum, topped crude, or the like,is supplied, the charging stock may be heated either to below crackingtemperature, for the purpose of efiecting its separation into thedesired components by fractional distillation without appreciablecracking, or relatively mild cracking conditions may be employed and theresultant products separated into the desired components by fractionaldistillation. Any desired low-boiling materials, such as gasoline, andany desired high-boiling materials such as heavy fuel oil, asphalticresidue, lubricating stock, or the like, may be separated from eachother and from materials of intermediate boiling characteristics in theinitial relatively mild cracking or fractional distilling step of theprocess, and either or both of said relatively low-boiling andrelatively highboiling material may, when desired, be recovered as finalproducts of the process, or subjected to further treatment in subsequentportions of the system. Intermediate components of the charging stock,or the products resulting from relatively mild cracking of the chargingstock, are separated into relatively low-boiling and high-boilingmaterials. The latter are cracked under independently controlledconversion conditions, the resultant vapors and liquid conversionproducts separated, said vaporous products subjected to fractionation toform a reflux condensate, which is returned to the same cracking stepfor further treatment, while fractionated vapors of the desiredend-boiling point from this stage of the process are subjected tocondensation and the resulting distillate and gaseous products collectedand separated. The low-boiling fractions of said intermediate componentsof the charging stock, or

the products resulting from relatively mild crack- -ing of the chargingstock, are subjected to cracking in an independently controlled crackingzone and the resultant hot conversion products are introduced into aseparate zone to which unvaporized residual liquid from one or both ofthe other cracking stages of the system are supplied and wherein theymay, when desired, be reduced to coke. Vaporous products from saidvaporizing zone are subjected to fractionation and the resulting refluxcondensate is returned for further cracking to the same cracking zone towhich the aforementioned reflux condensate is returned, whilefractionated vapors of the desired endboiling point from the lastmentioned fractionating step are subjected to condensation and the resultant distillate and gaseous products collected and separated.

The accompanying diagrammatic drawing illustrates one specific form ofapparatus in which the process of the invention may be conducted, andthe operation of the process will be more fully described in conjunctionwith the following description of the drawing.

Relatively wide boiling range charging stock of the character abovementioned may be supplied from any suitable source through line i andvalve 2 to pump 3, wherefrom it is fed through line it and valve 5 intoheating coil 6.

Heating coil 6 is disposed in a suitable furnace 1 and the chargingstock passing through this zone may be heated either to a relativelymild cracking temperature, or heated under non-cracking conditions to atemperature sufiicient to eiiect its subsequent separation into thedesired components. The heated products are discharged from heating coil6 through line 8 and valve 9 into column If] which functions as avaporizing, separating and fractionating zone and which, depending uponthe type of operation desired, be maintained under cracking, ornon-cracking conditions. Preferably, however,' no substantial crackingis allowed to occur in column IE! and vaporization of the heatingproduct supplied to this zone from coil 6 is assisted by substantiallyreducing the pressure imposed thereon as they pass through valve 9 inline 8, although when noncracking conditions are employed in heatingcoil 6, both the heating coil and column l9 may, when desired, bemaintained at substantially atmospheric or relatively lowsuperatmospheric pressure.

In case fractional distillation of the charging stock withoutappreciable cracking is desired in the above described initial step ofthe process, heating coil 6 may be eliminated when desired, in whichcase the charging stock may be heated sufficiently to effect itsfractional distillation by indirect heat exchange with variousrelatively hot intermediate and/or final products of the process,although provisions for accomplishing this are not illustrated in thedrawing. It is, of course, also within the scope of the invention topreheat the charging stock to any desired temperature, preferably belowthe cracking range, by any well known means, not shown, prior to itsintroduction into heating coil 6, regardless of whether or not it isheated to cracking temperature in coil 6.

In the particular case here illustrated, the charging stock is separatedin column l0 into four selected fractions of different boilingcharacteristics, although its separation into any desired number ofselected components is entirely within the scope of the invention. Thehighest boiling components of the charging stock, or of the productsresulting from its relatively mild conversion in coil 6, as the case maybe, are withdrawn as non-vaporous residual liquid from the lower portionof column I 0 and directed through line H and valve l2 to cooling andstorage, or to any desired further treatment. This product may comprisesuch materials as asphaltic residue, fuel oil, lubricating stock, or thelike, depending upon the nature of the charging stock, and theconditions of treatment to which it is subjected in coil 6. The lowestboiling components of the charging stock, or of the conversion products,comprising, for example, gasoline, naphtha and/or any other desiredlight distillates, are withdrawn, together with any normal gaseousmaterials, from the upper portion of column I0 and directed through linel3 and valve M to condensation and cooling in condenser Hi. Theresulting distillate and normally gaseous products are directed throughline l6 and valve l! to collection and separation in receiver I8.Uncondensed gases may be released from the receiver l9 and valve 20. Aportion or all of the distillate collected in receiver l8 may, whendesired, be withdrawn therefrom through line 2| and valve 22 to storage,or to any desired further treatment. When desired, regulated quantitiesof the distillate collected in receiver l8 may be recirculated, by wellknown means not illustrated, to the upper portion of column Hi to serveas a cooling and refluxing medium in this zone.

The invention also contemplates subjecting a regulated portion or all ofthe distillate collected in receiver 8 to cracking or reforming in aseparate stage of the system, in which event distillate may be directedfrom receiver I8 through line 23 and valve 24 to pump 25, by means ofwhich it is fed through line 26 and valve 21 to heating coil 28 forconversion therein in the manner to be later described.

The intermediate components of the materials supplied to column H] areseparated by fractionation in this zone into relatively low-boiling andhigh-boiling fractions, which are withdrawn from suitable intermediatepoints in column In through the respective lines 29 and 31 and directedthrough the respective valves 30 and 32 to pump 25 and pump 33respectively. The lowboiling fractions which may comprise, for example,such materials as high-boiling motor fuel fractions, naphtha, kerosene,or kerosene distillate, pressure distillate bottoms, light gas oil,etc., are directed from pump 25 through line 26 and valve 21 to crackingor reforming in heating coil 28.

The high-boiling fractions of the condensate from column l0, supplied topump 33 as described, are directed therefrom through line 34 and valve35 into line 36, wherefrom they are supplied through line 37 to heatingcoil 38.

A furnace 39 of suitable form supplies the required heat to the oilpassing through heating coil 38 to bring the same to the desiredcracking temperature, preferably at substantially superatmosphericpressure and the heated products are discharged from coil 38 throughline 40 and valve 4! into reaction chamber 42.

Chamber 42 is also preferably maintained at a substantialsuperatmospheric pressure and, although not here indicated, this zone ispreferably well insulated, to conserve heat, so that the hot conversionproducts supplied thereto undergo appreciable continued crackingtherein. Both vaporous and liquid conversion products are withdrawn fromthe lower portion of cham ber 42 and directed through line 43 and valve44 into vaporizing and separating chamber 45.

Chamber 45 is preferably maintained at a substantially reduced pressure,relative to that employed in the reaction chamber, by control of valve44 in line 43, whereby the conversion products supplied to this zone inliquid state are subjected to appreciable further vaporization. Theliquid residue remaining unvaporized in chamber 45 is withdrawn from thelower portion of this zone through line 46 and may be directed, all orin part, through line 41 and valve 48 to cooling and storage orelsewhere as desired, or a portion or all of this material may besupplied to another portion of the system for further treatment, as willbe later described. Vaporous products are directed from the upperportion of chamber 45 through line 49 and valve 50 to fractionation infractionator 5|.

Components of the vaporous products supplied to fractionator 5i, whichboil above the range of the desired final light distillate product ofthis stage of the process, are condensed in this zone as refluxcondensate which is directed from the lower portion of the fractionatorthrough line 52 and valve 53 to pump 54, wherefrom the reflux condensateis supplied through line 3'! and valve 55 to further cracking in theheating coil 38.

Fractionated vapors of the desired end-boiling point and normallygaseous products are directed from the upper portion of fractionator 5|through line 56 and valve 5? to condensation and cooling in condenser58, the resultant distillate and uncondensed gases passing through line59 and valve 68 to collection and separation in receiver 6|. Theuncondensed gases may be released from receiver 6! through line 62 andvalve 53 and the distillate recovered in this zone may be directedtherefrom through line 64 and valve 65 to storage or to any desiredfurther treatment. When desired, regulated quantities of the distillatecollected in receiver 6| may be recirculated, by well known means, notillustrated, to the upper portion of fractionator 5! to serve as acooling and refluxing medium in this zone.

The relatively low-boiling oils supplied as previously described toheating coil 28 are heated during their passage through this zone to thedesired cracking temperature, preferably at sub stantialsuperatmospheric pressure, by means of heat supplied to the heating coilfrom furnace 6B. When materials within the boiling range of gasoline aresupplied to heating coil 28, the conversion conditions maintained inthis zone are regulated to effect a substantial improvement in thequality of the gasoline, particularly with respect to its antiknockvalue, without excessively altering its boiling range. narily termedreforming and, since conditions within the reforming range are alsosuitable for cracking light distillates boiling above the range ofgasoline (such for example, naphtha, kerosene, kerosene distillate andthe like) to produce high yields of good quality gasoline therefrom, theinvention specifically contemplates supplying a mixture of lightdistillates from the initial step of the process to treatment in heatingcoil 28, a portion of the mixture comprising materials within theboiling range of gasoline and the remainder comprising materials, of thenature above mentioned, boiling above the range of gasoline. However, incase it is desired to recover the gasoline product separated from thecharging stock and/or produced in the initial step of the process, thematerial supplied to heating coil 28 may comprise only distillatesboiling above the range of gasoline from column Ii), in which case thecracking conditions employed in heating coil 2% may be somewhat milderthan those which may be utilized for reforming gasoline, or for crackinga mixture of gasoline and higher boiling distillates. In case thecharging stock does not contain an appreciable quantity of gasoline orgasoline fractions and no appreciable quantity of such materials isproduced in the initial step of the process, the invention, of course,contemplates supplying only higher-boiling distillates to heating coil28.

Heated products are discharged from heating coil 28 through line 6? andvalve 88 into chamber 69 which is operated as a vaporizing andseparating zone and wherein the high-boiling co1nponents of thematerials supplied to this zone may, when desired, be reduced tosubstantially dry coke. Chamber 59 is preferably maintained at asubstantially reduced pressure, relative to that employed at the outletfrom heating coil 28, in order to retard or arrest cracking in this zoneand assist vaporization, although chamber 6%) may, when desired, beoperated at a substantially superatmospheric pressure, suflicient toallow a controlled degree of continued cracking therein.

Preferably, at least a portion of the nonvaporous residual liquidwithdrawn, as previously described, from chamber 45 is directed throughvalve ill in line 46 to pump H by means of which it is supplied throughline 12 and valve 73 into chamber 69, wherein it is subjected to furthervaporization by virtue of the additional heat supplied thereto from themore highly heated products in chamber 69 and/or by virtue of a reducedpressure in chamber 69 relative to that employed in chamber 45. It isalso within the scope of the invention, when desired, to commingle atleast a portion of the non-vaporous residual liquid from chamber ie withthe nonconversion products passing from heating coil 28 Such treatmentis ordiinto chamber Bil, by introducing same into line 61', althoughwell known means for accomplishing this are not shown in the drawing. Itwill, of course, be understood that in case chamber 69 is operated at asubstantially lower pressure than chamber 45, pump H will not berequired and may be by-passed by well known means not illustrated.

When chamber 69 is operated as a coking zone, the coke produced may beallowed to accumulate therein until the chamber is substantially filled,or until its operation has been completed for any other reason,following which the accumulated coke may be removed in any well knownmanner, not illustrated, and the chamber cleaned and prepared forfurther operation. A plurality of coking chambers similar to chamber 69may, of course, be employed, although only one is shown in the drawing,and in such cases the chambers may be operated simultaneously or,preferably, are alternately operated, cleaned and prepared for furtheroperation. When liquid or semilicuid residue is produced in chamber 69,it may be withdrawn therefrom through line H and valve 15 to cooling andstorage or elsewhere as desired. This line may also serve as a means ofintroducing steam, water, or any other suitable cooling medium into thechamber after its operation has been completed and, preferably, after ithas been isolated from the rest of the system, in order to hastencooling and facilitate removal of the coke.

Vaporous products are directed from the upper portion of chamber 69through line 16 and valve Ti to fractionator 15, wherein theircomponents boiling above the range of the desired final light distillateproduct of this state of the system are condensed as reflux condensate.This reflux condensate is directed from the lower portion offractionator it through line .9 and valve to pump 8| by means of whichit is supplied through lins 82, valve 83, line 36 and line 31 to furthercracking in heating coil 38.

Fractionated vapors of the desired end-boiling point and normallygaseous products are directed from the upper portion of fractionator 18through line 8 and valve to condensation and cooling in condenser 35-,the resulting distillate and uncondensed gases pass through line 8'! andvalve 88 to collection and separation in receiver 89. Uncondensed gasesmay be released from receiver 83 through line 90 and valve 9|.Distillate collected in receiver 89 may be directed therefrom throughline 92 and valve 93 to storage, or to any desired further treatment.When desired, regulated quantities of the distillate collected inreceiver 89 may be recirculated, by well known means not illustrated, tothe upper portion of fractionator T8 to serve as a cooling and refluxingmedium in this zone.

The preferred range of operating conditions which may be employed toattain the desired results, in an apparatus such as illustrated andabove described, may be approximately as follows: The charging stock maybe heated in the initial cracking or fractional distilling step to atemperature ranging for example, from 600 to 800 F. or thereabouts. Asuperatmospheric pressure of from to 500 pounds or more per square inchis preferred in the heating stage of this step when temperatures withinthe cracking range are employed, and substantially atmospheric orrelatively lower superatmospheric pressure are preferred when thetemperature employed is below the cracking range. The presthe vaporizingand separating chamber.

sure employed in this first heating step may be substantially equalizedor reduced in the succeeding vaporizing, separating and fractionatingequipment. The cracking coil to which the rela tively high-boiling oilsare supplied may employ an outlet conversion temperature ranging forexample, from 800 to 950 F., preferably with a superatmospheric pressureat the point in the system of from 100 to 500 pounds, or thereabouts,per square inch. The succeeding reaction chamber is also preferablymaintained at a substantially superatmospheric pressure, which may besubstantially the same or somewhat lower than that employed at theoutlet from the communieating heating coil. The vaporizing andseparating chamber of this stage of the system is preferably operated ata substantially reduced pressure, relative to that employed in thereaction chamber, ranging for example, from substantially atmosphericpressure up to 150 pounds, or thereabouts, per square inch. Thefractionating, condensing and collecting portions of this stage of thesystem may employ pressure substantially the same or somewhat lower thanthat employed in The relatively light oil cracking coil may utilize anoutlet conversion temperature of the order of 900 to 1050 F. or more,preferably with a superatmospheric pressure at this point in the systemof from 250 to 1000 pounds, or thereabouts, per square inch. Thesucceeding chamber to which heated products from the light oil crackingcoil and residual liquid from the vaporizing and separating chamber aresupplied, may employ any desired pressure ranging from substantiallyatmospheric to a superatmospheric pressure of 150 pounds, orthereabouts, per square inch, although this zone is preferably operatedat substantially lower pressure than that employed in the vaporizing andseparating chamber. When operated as a coking zone, the temperaturemaintained in this chamber is preferably of the order of 800 to 900 ormore. The succeeding fractionating, condensing and collecting equipmentmay utilize pressure substantially the same or somewhat lower than thatemployed in the last mentioned chamber.

As an example of one specific operation of the process, conducted in anapparatus such as illustrated and above described; the charging stock isa light Smackover crude of about 26.6 A. P. I. gravity, containingslightly more than 18% of 437 F. end-point gasoline. The charging stockis mildly cracked in the first heating coil of the system at atemperature of approximately 800 F. and a superatmospheric pressure ofabout 250 pounds per square inch. This pressure is reduced in thesucceeding vaporizing, separating, and fractionating zone toapproximately 100 pounds per square inch and the products suppliedthereto are separated into a heavy residual fraction, which is suppliedto the coking chamber of the system, a light overhead fraction hav ingan end-boiling point of approximately 275 F., which is recovered, andtwo intermediate fractions, the relatively light intermediate fractionhas an initial boiling point of approximately 240 F. and an end-boilingpoint of approximately 550 F. This material is supplied to the light oilcracking coil of the system, wherein it is heated to outlet conversiontemperature of approximately 980 F. at a superatmospheric pressure ofabout 800 pounds per square inch, the resultant products beingdischarged therefrom into the coking chamber. The relatively heavyintermediate fraction, which has a boiling range of approximately 500 to690 F. is supplied to the heavy oil cracking coil, wherein it is heatedto outlet conversion temperature of approximately 950 F. at asuperatmospheric pressure of about 350 pounds per square inch. Theresultant heated products are introduced into the reaction chamber whichis maintained at substantially the same pressure and both vaporous andliquid products are supplied from the reaction chamber to the reducedpressure vaporizing and separating chamber. The latter zone is operatedat a superatmosph ric pressure of approximately 60 pounds per squareinch and a portion of the residual liquid remaining unvaporized in this-zone is recovered as a final product of the process, the remainderbeing supplied to the coking zone. Vaporous products from the vaporizingand separating chamber and vaporous products from. the coking zone areseparately subjected to fractionation for the formation of refluxcondensates and the recovery of overhead products comprising gasoline ofabout 400 F. end-boiling point. Reflux condensates from bothfractionating zones are returned to the heavy oil cracking coil forfurther treatment.

The above operation will produce, per barrel of charging stock, a totalof approximately 65% of 400 F. end-point gasoline (this figure includesthe low-end point gasoline recovered from the initial relatively mildcracking step) having an antiknock value of approximately '70. Inaddition, about 6% of good quality liquid residue, suitable for sale aspremium fuel oil, and about 55 pounds of low volital petroleum coke areremoved per barrel of charging stock. The remainder is chargeableprincipally to normally gaseous products and loss.

I claim as my invention:

1. In the process for the pyrolytic conversion of hydrocarbon oilswherein reflux condensate, formed as hereinafter described, is crackedin a heating coil and communicating enlarged reaction chamber maintainedat substantial pressure, the resultant vaporous and liquid conversionproducts separated, and the latter subjected to appreciable furthervaporization at substantially reduced pressure, the vaporous products,including those resulting from said further vaporization, subjected tofractionation for the formation of said reflux condensate which issupplied to said heating coil, fractionated vapors of the desiredend-boiling point subjected to condensation and the resultant distillaterecovered, the

improvement which comprises simultaneously heating charging stock forthe process, comprising an oil of relatively wide-boiling range, to alower cracking temperature than that employed in said coil andsufiicient to eiiect its substantial vaporization, separating theresulting heated materials into unvaporized oil and a plurality ofdistillate fractions, supplying one of said distillate fractions of saidcharging stock to said heating coil, wherein it is cracked with saidreflux condensate, supplying another of said distillate fractions, oflower boiling point than the first mentioned distillate fraction, to aseparate heating coil, wherein it is heated to a higher crackingtemperature, supplying conversion products from said separate heatingcoil to a separate enlarged chamber and introducing to the latterchamber at least a portion of said unvaporized oil and non-vaporousresidual liquid resulting from said further vaporization of said liquidconversion products, separating the com- 1 mingled materials in saidseparate enlarged chamber into vaporous and non-vaporous components,recovering the latter, subjecting said vaporous components tofractionation for the formation of reflux condensate, returning refluxcondensate from the last mentioned fractionating step to the firstmentioned heating coil for further cracking, subjecting fractionatedvapors of the desired end-boiling point from the last mentionedfractionating step to condensation, and recovering the resultingdistillate.

2. A process such as defined in claim 1, wherein the oil supplied tosaid separate heating coil contains a substantial quantity of fractionsboiling within the range of gasoline and the cracking conditionsemployed in said separate heating coil are controlled to effect asubstantial improvement in the antiknock value of said gasolinefractions.

3. A process such as defined in claim 1, wherein a distillate of lowerinitial-boiling point than the oil supplied to said separate heatingcoil is separated from the materials resulting from said heating of thecharging stock and recovered as a final product of the process.

4. A process such as defined in claim 1, wherein non-vaporous componentsof the materials supplied to said separating chamber are reduced thereinto coke.

5. A process such as defined in claim 1, wherein a regulated portion ofthe non-vaporous residual liquid resulting from said furthervaporization of the liquid conversion products of the first mentionedcracking step is recovered as a final product of the process and theremainder supplied to said separate chamber, wherein it is reduced tocoke.

6. A process such as defined in claim 1, wherein liquid residue ofhigher boiling characteristics than the oil supplied to the firstmentioned heating coil is separated from the products resulting fromsaid heating of the charging stock and is recovered as a final productof the process.

'7. A hydrocarbon oil conversion process which comprises heating acharging oil of relatively wide boiling range to cracking temperatureand separating the same into vapors and unvaporized oil fractionallycondensing the vapors to form a plurality of condensates, heating one ofsaid condensates under pressure to higher cracking temperature than saidcharging oil in a heating coil and separating the same into vaporous andliquid conversion products in a separating zone, simultaneouslysubjecting another of said condensates, of lower boiling point than thefirstmentioned condensate, to higher cracking temperature under pressurein a second heating coil and subsequently discharging the same into areduced pressure chamber, removing liquid conversion products from saidseparating zone and introducing the same to said reduced pressurechamber, also introducing to said chamber at least a portion of saidunvaporized oil, further distilling said liquid products and unvaporizedoil in the chamber, and fractionating and condensing the vaporousproducts from the separating zone and from said chamber.

. KENNETH SWAR'I'WOOD.

